Evaluation on the practical value of prenatal screening for Down syndrome among women of advanced maternal age

Objective To assess the practical value of prenatal screening for down syndrome among pregnant women of advanced maternal age.Methods Pregnant women with advanced maternal age who did prenatal screening for Down syndrome(DS)in Taizhou hospital from January 2006 to December 2011 were selected and tested for the serum levels of AFP and free-βHCG during the second trimester by time-resolved immunofluorescence method.Final diagnosis was confirmed by chromosome examination of amniotic fluid cell or allantoic venous blood cells.The diagnostic results were compared with the follow-up outcome of the pregnancies.Results Among 4187 women of advanced maternal age,32 were found to have 21-trisomy(0.76%).Also,there were 13 and one who carried 18-trisomy(0.31%)and 13-trisomy(0.02).Out of 1076 women screened for DS,648 were at high risk with the incidence of 1.76%for 21-trisomy and of 15.15%for 18-trisomy.Only 5 women were found to have other chromosomal abnormalities among 428 women with low risk.The difference was statistically significant between the two sets of data(P0.01).Conclusions Noninvasive prenatal screening in women of advanced maternal age combined with amniotic chromosome examination may significantly increase the diagnostic efficiency for DS especially for 18-trisomy detection.